1. Field of the Invention
The present invention relates to a rotary operation device used to operate an electronic device mounted in a vehicle.
2. Description of Related Art
A rotary operation device is conventionally known as an operation device mounted in various electronic devices. When being mounted in a vehicle, such as an automobile, for example, such a rotary operation device is used to operate an electronic device in the vehicle, specifically, an air conditioner, a car navigation system, or a car audio system. Related Art 1 discloses such a rotary operation device, which includes a rotary operation member, a rotation detector, and a rotational force transmission member. The rotary operation member is rotated around a specific rotation axis. The rotation detector detects a rotary operation amount of the rotary operation member. The rotational force transmission member transmits a rotational force of the rotary operation member to the rotation detector. The rotary operation member has a first gear on an entire periphery of the rotation axis. The rotational force transmission member has a second gear and a transmission axis. The second gear is engaged with the first gear and is thus rotated in association with rotation of the rotary operation member. The transmission axis rotates integrally with the second gear. The transmission axis, which is reliably positioned to the rotation detector and is coupled therewith, transmits the rotation to the rotation detector. Thus, an output from the rotation detector varies in accordance with the operation amount of the rotary operation member. In other words, the operation position of the rotary operation member and the output from the rotation detector are in a constant relationship with each other in the rotary operation device.
The rotary operation device should be assembled such that the first gear of the rotary operation member and the second gear of the rotational force transmission member are provided in a proper engagement position where the gears are surely engaged in a proper phase relationship. With the gears assembled in the proper engagement position, the rotary operation member is rotated to a predetermined operation position, and then the rotation detector outputs an appropriate signal associated with the operation position or operation amount. However, in a case where the teeth of the first gear and the teeth of the second gear are misaligned from the proper engagement position even at one tooth in assembly, even when the rotary operation member is rotated to the operation position or operation amount, the rotation detector outputs a signal different from the appropriate signal or there is an error in the output signal. For instance, in a case where the rotation detector is of a variable resistance type and the rotary operation member and the rotational force transmission member are assembled in a position misaligned from the proper engagement position, even when the rotary operation member is rotated to the predetermined position, the rotation detector outputs a signal based on a resistance value different from a resistance value that renders the appropriate signal. In a case where the rotation detector is a rotary encoder that outputs pulses and the rotary operation member and the rotational force transmission member are assembled in a position misaligned from the proper engagement position, a pulse signal is likely to be output at an operation amount different from an operation amount of the rotary operation member at which a predetermined pulse signal is output. Specifically, the rotation detector and the rotational force transmission member are reliably positioned and assembled. Thus, when the rotary operation member and the rotational force transmission member are assembled with the first gear and the second gear misaligned from the proper engagement position, the malfunctions above occur.
In this regard, the rotary operation device disclosed in Related Art 1 has a confirmation mark on at least either of the rotary operation member or the rotational force transmission member. This confirmation mark enables confirmation of the first gear and the second gear in the proper engagement position during assembly of the rotary operation member and the rotational force transmission member. This facilitates assembly of the members in the proper engagement position.
[Related Art 1] Japanese Patent Laid-Open Publication No. 2007-296956
However, even when the rotary operation member and the rotation detector are assembled while the confirmation mark is being checked, the rotary operation member and the rotation detector are possibly assembled with the first gear and the second gear in a position misaligned from the proper engagement position. Thus, a concern over misassembly of the members still remains.